Fiber drafting analyzer



Oct. 24, 1961 R. A. SMITH FIBER DRAFTING ANALYZER Filed Oct. 11, 1957United States Patent 3,005,340 FIBER DRAFTING ANALYZER Robert A. Smith,Drexel Hill, Pa., assign-or to American Viscose Corporation,Philadelphia, Pa., a corporation of Delaware Filed Oct. 11, 1957, Ser.No. 689,588 2 Claims. (Cl. 73-159) This invention relates to a testingdevice for measuring the force required to draft a sliver, roving orlike bundle of fibers to facilitate the study of the frictionalresistance to slippage of staple fibers past one another in thedirection of their longitudinal axes during the attenuation of thesliver into roving and the subsequent attenuation of the roving.

In the production of yarn from staple fibers, whether natural orman-made, the randomly arranged, relatively short fibers are firstsubjected to a process known as carding in order to arrange the fibersin generally parallel relationship. The carding process results in whatis known as a sliver which is an elongated rope-like structure inuntwisted form whereinthe fibers are rather loosely held together. Thesliver is then drafted or attenuated so that the fibers are slippedendwise past one another to greatly increase the length of the structureand consequently decrease the cross-sectional area. As the cross-sectionis decreased the bundle of filaments is twisted very slightly in orderto hold the fibers together. After a considerable amount of attenuationthe strand reaches a stage known as roving wherein the fibers are stillarranged in generally parallel relation and the tensilestrength is stillvery low because there is only a slight amount of twist. The roving isthen spun into a yarn strand. 7

The force required for drafting sliver and roving of different materialsvaries consider-ably, as does the total amount of attenuation which itis possible to obtain while still producing a yarn of substantialstrength. In the operation of a textile mill it is highly important toknow the frictional forces involved in slipping the fibers of the sliveror roving past one another. Among the factors affecting these forces isthe finish applied to the fibers. As is generally known, variousfinishes are applied to staple fibers, the particular finish dependingin large degree upon the physical characteristics of the fiber itself.One desirable attribute of a finished fiber is that its frictionalcharacteristics should not change with age or with variations inatmospheric conditions It is a matter of common knowledge that a finishwhich is entirely satisfactory when first applied, after aging or underdifferent humidity conditions may develop a tendency to changeitscoeihcient of friction sufliciently to cause adhesion of the fibers toone another, thus preventing the roving from drafting when subjected tonormal drafting force.

While it is obvious that a knowledge of the frictional forces involvedin drafting would enable better finishes to be developed and would be ofvalue to the mill operator in setting his machinery for the ideal twistfor the particular material that was being operated upon, heretofore ithas not been possible to accurately evaluate the frictional resistanceof the fibers to slip past one another under practical draftingconditions.

It is the primary object of the present invention to provide a devicewherein the actual drafting conditions encountered in a mill may besimulated and by means of which device the frictional forces involvedduring drafting may be accurately measured.

It is a more general object of this invention to provide a research toolwhich will facilitate the study of the 3,005,340 Patented Oct. 24, 19612 frictional forces involved in drafting sliver, roving or like bundlesof fibers.

Other and more particular objects, features, and advantages of theinvention will become apparent as the description of a preferredembodiment thereof proceeds.

Referring now to the drawing;

The figure is a diagrammatic view partially in side elevation of adevice constructed in accordance with this invention.

- The device generally comprises a pair of input feed rolls 10 and 11and a pair of output rolls 12 and 13. The lower input feed roll 11 issecured to a shaft 14 mounted in stationary bearings while the upperinput feed roll 10 is secured to a shaft '15 mounted in a bearing block16 slidably mounted upon a pair of guide pins 17 and 18 fixed in themain framework generally indicated at 19. A plunger 20 is secured to thebearing block 16 and a spring 21 extends between the upper -end of saidplunger and the framework 19 to urge the upper feed roll 10 intoengagement with the lower feed roll 11. The plunger 20 is provided witha cutout portion 22 extending into which is a flattened shaft 23rotatably mounted in the framework 19 and provided with an operatinghandle 24. By moving the handle 24 downwardly from the position shown inthe drawing, the flattened portion of the shaft 23 is brought intoengagement with the cutout portion 22 to thereby raise the plunger 20against the action of the spring 21 and release the feed roll 10 fromengagement with the feed roll 11.

The output roll .12 is secured to a shaft 25 rotatable in stationarybearings and the output roll '13 is secured to a shaft 26 mounted in amanner identical to that of the shaft 15 of the input feed roll 10.

The input feed rolls 10' and 11 are drivingly connected to the outputrolls 12 and 13 by means of a gear 27 fixed to the shaft 14 and a gear28 secured to the shaft 25, said gears being interconnected throughapinion 29. The gearing arrangement is such that the output rolls aredriven at a speed slightly in excess of the speed of the input feedrolls and by changing the various gears the ratio of the speed of theoutput rolls to that of the input feed rolls may be varied as desired.

Splined tothe shaft 14 at the end opposite the gear 27 is a gear 30 withwhich is meshed a drive gear 31 splined on ashaft 32 to which is secureda sprocket 33 driven by a sprocket chain 34 which in turn is driven froma suitable motor, not shown.

The sliver, rovingor like bundle of fibers 35 whose frictionalresistance to drafting it is desired to test is fed between the inputfeed rolls 10 and 11 and thence upwardly over a sensing roller36 freelyrotatable upon a shaft 37 extending between the arms of a yoke 38provided on the lower end of a plunger 39 of an electronic strain gauge,the purpose of which will presently be described. From the roller 36 thesliver or the like is extended downwardly and between the output rolls12 and 13. In the textile art the point of engagement between rolls isreferred to as the nip of the rolls, since it is at this point that thematerial passing between the rolls is squeezed or nipped. From thedrawing it will be observed that the two sets of rolls are mounted onparallel axes and that planes tangential to the nips of the two sets ofrolls intersect at a right angle and it will also be observed that thesensing roller 36 is tangent to the nip of the output rolls 12 and 13.

Since the roller 36 is freely rotatable, the drafting of the sliver orroving caused by the differences in speed between the output rolls andthe input feed rolls will take place between the nip of the output rollsand the point where the sliver or roving leaves the roller 36 and thefrictional resistance offered by the slippage of the fibers past oneanother during this drafting or attenuation of the strand will produce adownward pull on the roller 36 and the plunger 39. The plunger 39 ismounted within a sleeve 40 secured in an arm 41 adjustably mounted upona post 42 forming a part of the framework of the device and said plungeris operatively connected through a. transducer 43 to a suitablerecording device 44. The particular transducer and recording deviceemployed are not of the essence of this invention but preferably therecording device is of a type which indicates on a graph the variationsin vertical movement of the roller 36 as converted into electricalenergy by the transducer 43.

A pointer 45 is carried by the arm 41 and by adjusting the height ofsaid arm in accordance with the indications of said pointer incooperation with a scale 46 provided upon the post 42, the height of thesensing roller 36 may be adjusted so that a distance between the nip ofthe output rolls '12 and 13 and the point where the sliver or rovingleaves the sensing roller is only slightly in excess of the length ofthe staple fibers making up the strand. If conditions similar to thoseencountered in a mill are to be simulated, it is essential that thedistance between the sensing roller 36 and the output rolls beadjustable since the sensing roll 36 of the present device in effecttakes the place of the back feed rolls of standard textile machines andif this distance is substantially greater than the fiber length, almostno force will be required to completely separate the fibers and breakthe strand, and if this distance is too short there will be a tendencyto elongate or break the individual fibers rather than to slip thefibers past one another.

Since the sensing roller 36 is an idler roller, even though iteffectively serves as a drafting point, it is capable of accuratelymeasuring the frictional forces involved in drafting the sliver,unaffected by other factors which are present when an attempt is made totake readings from the drafting rolls themselves.

Since, as previously mentioned, the present device is primarily aresearch tool, it is desirable that the electronic strain gaugecomprising the sensing roller 36 and recorder 44 be of the type whereinthe speed of the chart of the recorder may be varied or regulated. Thereare a number of such gauges on the market and one which has been foundto be satisfactory is manufactured by the Brush Electronics Company ofCleveland, Ohio. The Brush gauge comprises a transducer, amplifier,direct writing oscillograph and a sensing element herein shown as theroller 36 and is equipped with a three-speed transmission whereby chartspeeds of 1, and 25 units per given length of time may be obtained. Bychanging the ratio of the drive gears 30 and 31 the sliver or roving maybe made to advance through the feed rolls and 11 at the same speed asthe chart movement or at a known fraction or multiple thereof.

Having thus described a preferred embodiment of the invention, what isclaimed is:

A device for measuring the force required to draft a sliver, roving orlike bundle of fibers, comprising a first set of drafting rolls, meansfor driving said drafting rolls at a preselected speed, a second set ofdrafting rolls having axes parallel to the axes'of said first set, meansfor driving said second set from said first set at a greater rate ofspeed than said first set, said sets of drafting rolls being sopositioned that planes tangential to the nips of the two sets of rollsintersect at an angle, a nicely rotatable force sensing roller locatedintermediate the two sets of drafting rolls, said sensing roller beingtangent to the plane of the nip of said second set of drafting rollswhereby the sliver or the like running between the two sets of draftingrolls and around said sensing roller will be attenuated between saidforce sensing roller and said second set of drafting rolls, meansoperatively connected to said sensing roller for recording the tensionon the sliver or the like during its attenuation, means for fixedlyadjusting the position of said sensing roller so that the distancebetween the point where the sliver or the like leaves said sensingroller and enters the nip of said second set of drafting rolls isslightly greater than the length of the fibers making up said sliver orthe like, and scale means indicating the adjusted position of saidsensing roller.

2. A device for measuring the force required to draft a sliver, rovingor like bundle of fibers, comprising a first set of drafting rolls, asecond set of drafting rolls, means for driving said sets of rolls atpreselected rates of speed with the second set being driven at a greaterspeed than the first set, said sets of drafting rolls being sopositioned that planes tangential to the nips of the two sets of rollsintersect at a right angle, a freely rotatable force sensing rollerlocated intermediate the two sets of drafting rolls, said sensing rollerbeing tangent to the plane of the nip of said second set of draftingrolls whereby the sliver or the like running between the two sets ofdrafting rolls and over said sensing roller will be attenuated betweensaid force sensing roller and said second set of drafting rolls, meansoperatively connected to said sensing roller for recording the tensionon the sliver or the like during its attenuation, means fixedlyadjusting the position of said sensing roller so that the distancebetween the point where the sliver or the like leaves said sensingroller and enters the nip of said second set of drafting rolls isslightly greater than the length of the fibers making up said sliver orthe like, and scale means indicating the adjusted position of saidsensing roller.

References Cited in the file of this patent UNITED STATES PATENTS

